Pupils lack basic maths skills, such as knowing how to multiply, in about two-fifths of primary schools and half of secondary schools in Wales. That's according the school's inspectorate, ESTYN, following inspections that were carried out between 2010-2012.
The report says that pupils cannot apply advanced numeracy skills because they are struggling with the basics. Some pupils struggle with decimals, fractions and percentages, such as understanding the relationships between 2/5ths, 0.4 and 40%.
Other aspects that need to be improved are the tracking and monitoring of pupils' progress. Only a minority of primary schools and a few secondary schools have effective systems to track pupils' progress in numeracy beyond their maths lessons.
More top news
Helping young people 'earn, learn or serve' is among the policies Plaid Cymru will focus on ahead of the next election.
Trains have been cancelled and roads closed across Wales today after Storm Brian has been causing disruption.
The Pride of Britain Awards are less than a month away, and today we find out who'll represent Wales in the Fundraiser of the Year category.